Multilayer container, method for manufacturing same, and method for manufacturing reclaimed polyester

Abstract

Provided is a multilayer container including a polyester layer containing a polyester resin (X), and a polyamide layer containing a polyamide resin (Y), a yellowing inhibitor (A), and an oxidation accelerator (B). The content of the polyamide resin (Y) is from 0.05 to 7.0 mass % relative to the total amount of all polyamide layers and all polyester layers. The yellowing inhibitor (A) is a dye, and the content of the yellowing inhibitor (A) is from 1 to 30 ppm relative to the total amount of all polyamide layers and all polyester layers.

The invention claimed is: 
     
       1. A multilayer container comprising:
 a polyester layer comprising a polyester resin (X); and 
 a polyamide layer comprising a polyamide resin (Y), a yellowing inhibitor (A), and an oxidation accelerator (B); 
 a content of the polyamide resin (Y) being from 0.05 to 7.0 mass % relative to a total amount of all polyamide layers and all polyester layers; 
 the yellowing inhibitor (A) being a dye; and 
 a content of the yellowing inhibitor (A) being from 1 to 30 ppm relative to the total amount of all polyamide layers and all polyester layers. 
 
     
     
       2. The multilayer container according to  claim 1 , wherein the polyester resin (X) comprises a constituent unit derived from a dicarboxylic acid and a constituent unit derived from a diol, 80 mol % or greater of the constituent unit derived from a dicarboxylic acid being a constituent unit derived from terephthalic acid, and 80 mol % or greater of the constituent unit derived from a diol being a constituent unit derived from ethylene glycol. 
     
     
       3. The multilayer container according to  claim 1 , wherein the polyamide resin (Y) comprises a constituent unit derived from a diamine and a constituent unit derived from a dicarboxylic acid, 80 mol % or greater of the constituent unit derived from a diamine being a constituent unit derived from xylylene diamine, and 80 mol % or greater of the constituent unit derived from a dicarboxylic acid being a constituent unit derived from adipic acid. 
     
     
       4. The multilayer container according to  claim 1 , wherein the yellowing inhibitor (A) is an anthraquinone-based dye. 
     
     
       5. The multilayer container according to  claim 1 , wherein the multilayer container is a hollow multilayer container. 
     
     
       6. The multilayer container according to  claim 1 , wherein the multilayer container has a 2 to 5 layer structure, and an outermost layer is a polyester layer. 
     
     
       7. The multilayer container according to  claim 1 , wherein the multilayer container has a 3 to 5 layer structure, and the outermost layer and an innermost layer are polyester layers. 
     
     
       8. The multilayer container according to  claim 1 , wherein the oxidation accelerator (B) is a compound comprising a transition metal. 
     
     
       9. The multilayer container according to  claim 8 , wherein the transition metal is at least one selected from the group consisting of cobalt, iron, manganese, and nickel. 
     
     
       10. The multilayer container according to  claim 1 , wherein the polyamide layer further comprises a greening inhibitor (C). 
     
     
       11. The multilayer container according to  claim 10 , wherein the greening inhibitor (C) is at least one selected from the group consisting of anthraquinone-based dyes and azo-based dyes. 
     
     
       12. The multilayer container according to  claim 1 , wherein the polyamide layer further comprises a polyester resin (Z). 
     
     
       13. The multilayer container according to  claim 12 , wherein a content of the polyester resin (Z) in the polyamide layer is from 5 to 70 mass %. 
     
     
       14. A method for manufacturing a multilayer container comprising:
 a polyester layer comprising a polyester resin (X); and 
 a polyamide layer comprising a polyamide resin (Y), a yellowing inhibitor (A), and an oxidation accelerator (B); 
 a content of the polyamide resin (Y) being from 0.05 to 7.0 mass % relative to a total amount of all polyamide layers and all polyester layers; 
 the yellowing inhibitor (A) being a dye; and 
 a content of the yellowing inhibitor (A) being from 1 to 30 ppm relative to the total amount of all polyamide layers and all polyester layers; and 
 the manufacturing method comprising: 
 a step 1 of mixing the polyamide resin (Y), the yellowing inhibitor (A), and the oxidation accelerator (B) to prepare a polyamide resin mixture; 
 a step 2 of co-injection molding the polyamide resin mixture and a polyester resin composition containing the polyester resin (X), and thereby obtaining a multilayer preform; and 
 a step 3 of blow molding the multilayer preform. 
 
     
     
       15. The method for manufacturing a multilayer container according to  claim 14 , wherein in step 1, a greening inhibitor (C) is further mixed. 
     
     
       16. The method for manufacturing a multilayer container according to  claim 14 , wherein in step 1, a polyester resin (Z) is further mixed. 
     
     
       17. The method for manufacturing a multilayer container according to  claim 14 , wherein in step 1, a polyamide resin or polyester resin, the yellowing inhibitor (A), and the oxidation accelerator (B) are kneaded and then mixed with the polyamide resin (Y). 
     
     
       18. The method for manufacturing a multilayer container according to  claim 14 , wherein the oxidation accelerator (B) is a compound comprising a transition metal. 
     
     
       19. The method for manufacturing a multilayer container according to  claim 14 , wherein the yellowing inhibitor (A) is an anthraquinone-based dye. 
     
     
       20. A method for manufacturing a recycled polyester, the method comprising recovering polyester from the multilayer container described in  claim 1 .